P0730 means the TCM (transmission control module) saw an incorrect gear ratio. The TCM monitors the gear ratio of which ever gear it is commanding by watching the speed sensors in the transmission. This problem is definitely going to require a high end scan tool to look at the freeze frame to see what gear the transmission was in when the code set. You'll also have to monitor the speed signals. If everything is ok electrically, there could be something going on inside the transmission. Make sure the fluid level is good.

Still don't understand your V code. I think you are confusing V with the letter U. U0126 is the steering angle sensor module lost communications ABS controller. The sensor is used by that system so it knows the position of the steering wheel for yaw control when you over steer.

You'll need that same enhanced scan tool to see if the angle sensor module is actually active on the data bus. If the module isn't active, you have to figure out why. Is it missing power or ground, has data bus problems, or has the module failed internally? No way to know unless testing is done.

I have a feeling that you might be over your head if you plan on attempting to figure this out yourself.

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